Sociodemographic versus clinical factors associated with incomplete and prolonged courses of radiotherapy.

Abstract

139 Background: Radiotherapy is an important component of therapy for many patients with cancer. However, some patients have difficulty completing recommended courses of radiotherapy in a timely manner. Unfortunately, prolonged or incomplete courses of therapy are associated with higher rates of relapse and lower survival rates, particularly for head and neck and cervical cancers. However, the most important drivers of incomplete or prolonged treatment courses are unclear. Our objective was to quantify associations between sociodemographic and clinical factors and incomplete and prolonged treatment courses. Methods: We extracted data for all patients treated with radiotherapy at a large metropolitan academic institution from 2018 – 2022 from the radiotherapy treatment planning software and from the medical record. Incomplete radiotherapy courses were defined as lack of completion of all planned radiotherapy fractions based on the treating physician’s prescription. Prolonged radiotherapy courses were defined as prolonging treatment by more than 5 days and missing 5 or more fractions, a clinically meaningful delay that can impact cancer outcomes. The primary endpoint was a composite endpoint consisting of incomplete and prolonged radiotherapy courses. Multivariable logistic regression was utilized to quantify associations between incomplete and prolonged treatment courses with age, sex, distance to facility, ZIP code social deprivation index (SDI), insurance status, radiotherapy modality, number of radiotherapy fractions, and treatment site. Models were also adjusted for year-quarter. Results: A total of 9950 cases were included, including 352 (6.5%) and 642 (3.5%) incomplete and incomplete/prolonged radiotherapy courses, respectively. In multivariable logistic regression analyses, factors associated with increased risk of incomplete or prolonged radiotherapy courses included ZIP code SDI > 80 (8.8%, OR 1.43, 95% CI = 1.13-1.80, P=.003), Medicaid insurance (12%, OR 1.92, 1.47-2.50, P<.001), more than 5 fractions of radiotherapy (12.8%, 9.7%, 14.6%, and 13.1%, for 6-10, 11-20, 21-29, 30+ fractions, respectively; P<.001), and treatment site of female pelvis (23.9%, OR 3.27, 2.26-4.78, P<.001). Conclusions: Prolonged or incomplete radiotherapy courses were associated with disadvantaged neighborhoods, Medicaid insurance, higher number of radiotherapy fractions, and female pelvic cancers. Each of these factors is related to social determinants of health and time/financial burden of treatment, including female pelvic cancers (predominantly locally advanced cervical cancer, associated with lower socioeconomic status), underscoring the impact of social determinants of health on patient’s ability to undergo radiotherapy.